[RC232] Please confirm if packet_length should be configured to total number of bytes including overhead (26 in my case) or only effective payload (15 in my case)

The packet length parameter only refers to UART bytes. The RF overhead you do not have to think about.
So you set it to 15.

Last Update: August 8, 2017  

December 13, 2016   1147    RC232 Q&A